This invention relates to a looper apparatus for a tufting machine, and more particularly to a looper apparatus for imparting linear motion to the looper hooks. Previous looper configurations for tufting machines have generally been designed to impart limited arcuate, reciprocable motion to the looper hooks, whether they are cut pile hooks or loop pile hooks.
The looper apparatus which is predominantly used in commercial tufting machines today includes a looper bar supporting the looper hooks and in turn supported upon a curved rocker arm, the lower end of which is journaled about an idler or looper shaft. Reciprocable motion is imparted to the curved rocker arm by a reciprocable looper shaft or rock shaft which is reciprocably driven, and which is pivotally linked to the rocker arm. The degree of arcuate motion of the looper hooks is determined by the radial distance between the looper hooks and the axis of the lower idler shaft. In order to minimize the curvature of the arcuate travel of the looper hooks, the idler shaft must be located as far away from the looper hooks as possible in order to increase the radius. This involves locating the idler shaft as low as possible in the machine and maintaining the idler shaft in substantial vertical alignment with the reciprocal path of the needles.
The greater the radial distance between the looper hooks and the axis of the idler shaft, the greater the mass of the rocker arm and other cooperative elements. The greater the mass of the moving parts, the greater energy requirements for driving the rocker arm, the greater opportunity for vibration of the moving parts, and the greater is the obstruction in the lower part of the machine to maintain and service the machine.
Some representative examples of prior art tufting machines incorporating the above described looper apparatus including a rocker arm for driving the loop pile hooks are U.S. Pat. Nos. 3,633,523 by Card; 3,919,953 by Card et al.; 4,301,752 by Ingram, et al.; and 4,369,720 by Beasley.
In U.S. Pat. No. 4,759,199, an attempt was made to develop a linear motion looper apparatus for a tufting machine. Although this apparatus operated satisfactorily for limited sample runs, in actual commercial operation, the bearings wore out too quickly for satisfactory operation. The present invention is addressed primarily to overcoming the shortcomings of the machine described in U.S. Pat. No. 4,759,199.